In power receiving and transforming equipment, there is installed a closed switchboard (referred to as a switchgear). It is constructed by housing the following items in an enclosure; a vacuum circuit breaker for interrupting a load current or a fault current; a disconnector and an earthing switch for ensuring the safety of a worker who conducts maintenance work on a load; detectors for system voltage and current; a protective relay; and the like.
With respect to this type of switchgear, it is required to give consideration to the position and direction of power cables connecting the switchgear. Therefore, it has been desired that the switchgear can cope with the position and direction of the power cables.
In one of measures for the improvement of this regard, various positions and directions of power cables cope with each other as follows. Multiple switches are housed in respective vacuum cases and integrally molded; this molded portion is provided with terminals for power cable connection; and these terminals for power cable connection are protruded in various directions. (Refer to Patent Document 1, for example.)
[Patent Document 1] JP-A-2000-306474 (FIG. 16)
The above-mentioned switchgear is so constructed that the following can be implemented with respect to multiple switches, buses, terminals for power cable connection, and the like housed in an enclosure having a door: the disposition of them in the enclosure can be changed to cope with various positions and directions of power cables.
With respect to power receiving and transforming equipment having this type of switchgear, users' demands have been diversified. An example will be taken. The type of load and operating conditions differ depending on the purpose of use on the customers' sites. When a distribution system is planned, therefore, consideration is given to the requirements for safety, reliability, the maintenance of operation, and expected increase in load. In this planning for power distribution, it is also required to take the following into account: control of a circuit breaker, a disconnector, an earthing switch, and the like constructing the power receiving and transforming equipment and monitoring and measurement of their voltage, current, power, and the like.
In this case, important considerations are how the installation space for the above devices and monitoring and measuring instruments should be reduced for size and weight reduction and suppression of investment in installation.
Further, it is important to give sufficient consideration to safety as well as a wide variety of users' other demands. For example, some of important considerations are to enhance the safety of installed switchgear against earthquakes and the like and to fulfill a failsafe function in a failure in an operating system for a circuit breaker.